A fuel cell system includes a solid polymer electrolyte membrane, one side of which is provided with a cathode and the other side of which is provided with an anode. This system purports to provide an external load power generated depending on an electrochemical reaction between oxygen in air supplied to the cathode and hydrogen supplied to the anode.
A fuel cell stack is formed by vertically stacking a plurality of unit cells, each including: a cathode, through which an oxidation gas flows; an anode, through which a reduction gas flows; and a polymer electrolyte membrane.
Among these, a separator is provided in the fuel cell system to perform the following functions. The separator functions as a passage for supplying the reduction gas and the oxidation gas to the cells in the fuel cell stack, and as a passage for supplying cooling water to cool the stack, and as a passage for transferring generated current.
Such a separator should have air tightness or liquid tightness so that the reduction gas and the oxidation gas are not mixed with the cooling water. To ensure air tightness, the surface of the separator is provided with a gasket using a rubber seal to maintain fluid or gas tightness and to keep-up a surface pressure.
FIGS. 1 and 2 illustrate the separator 500 and the gasket 502, in which an adhesive 504 is applied on the surface of the separator 500 and then the gasket 502 made of a rubber seal is formed thereon via injection.
The separator 500 is manufactured via introduction of a material, formation of a passage (stamping), conductive surface treatment and integrated gasket injection, in order. The integrated gasket 502 of the separator 500 is formed by performing integrated gasket injection on the surface of the separator 500 under a condition of an edge of the separator 500 being held by a gasket injection mold under pressure.
The separator 500 having the integrated gasket 502 should be exposed to a temperature of 200° C. or higher for a long period of time so as to cross-link a gasket material, undesirably causing process interference problems with the conductive surface treatment. In the case where the gasket material escapes from the gap between the separator and the gasket mold upon integrated injection, it should be removed using deburring. In the course of deburring, physical damages to the surface of the separator may occur, remarkably increasing defect rates.
To manufacture a finished separator, the aforementioned four processes should be carried out. When defects are created during the gasket injection, the manufacturing costs of the preceding processes may be undesirably added to defect costs.
The foregoing is intended merely to aid in the understanding of the background of the present inventive concept, and is not intended to mean that the present inventive concept falls within the purview of the related art that is already known to those skilled in the art.